When NumPy is built, information about system configuration is
recorded, and is made available for extension modules using Numpy’s C
API. These are mostly defined in numpyconfig.h (included in
ndarrayobject.h). The public symbols are prefixed by NPY_*.
Numpy also offers some functions for querying information about the
platform in use.

For private use, Numpy also constructs a config.h in the NumPy
include directory, which is not exported by Numpy (that is a python
extension which use the numpy C API will not see those symbols), to
avoid namespace pollution.